This invention relates to watchcases, particularly to those watchcases in which the periphery of the glass wholly covers the caseband and appears around a transparent glass part in lieu of the bezel of conventional watchcases.
With the known watchcases of this type, the glass periphery is given the appearance of a bezel by depositing a thin layer of metallization either over a glass flange or on the walls of a groove provided in the lower face of said flange (Swiss Patent CH-B-336,334).
While the metallization formed over the outer glass face, being exposed to wear in contact with foreign bodies, is not very durable, that deposited on the walls of a groove formed in the lower face of the glass flange offers only a narrow range of ornamental possibilities. Firstly, that known solution does not provide a tight seal between the glass and the caseband. Moreover, it is applicable only to circular glasses, because of the mode of fixation of the glass. It is also limited to glasses made out of a relatively soft material, because of the shape which the glass is to be given. A hard glass, such as a sapphire or a tempered mineral glass, as commonly used nowadays with highgrade watches, can, indeed, not be given that shape. Finally, the metallization disclosed by that known solution may only produce surfaces with plain colors having a metallic glance.
Thus, it appears that this known solution is suitable only for very indifferent watchcases which are manufactured in large series of identical pieces. Now, with high-grade watches, a large number of one and the same watchcase pattern is seldom ordered. Therefore, the manufacturers of the casings for such watches are reduced to small-scale thus expensive production. If they have to manufacture different watchcase designs for watches of the same shape, sizes and caliber, they must have many skilled workmen at disposal as well as an important mechanical equipment to carry out at the same time the finishing operations for every watchcase pattern ordered in order to be able to deliver these watchcases at once and not in driblets.
However, it is known to provide the glass periphery with decorative motifs breaking the monotony of extensive plain surfaces by forming reflecting facets on the lower glass face (Swiss Patent CH-B-435,123). This solution does, however, not confer on the glass periphery the appearance of a framing taking the place of the bezel of the conventional watches. It aims, on the contrary, to give one illusion that the dial extends near to the watchcase edge, where a metallic watchcase part, necessary to the protection of the glass, still subsists, and which, though it is very narrow, nevertheless appears as a bezel that must be finished as such, but in a very restricted range of possible aesthetical effects. Furthermore, this solution is, like the first one referred to hereabove and for the same reasons, confined to glasses made out of a relatively soft material.
Watchcases are also known in the art, the bezel of which, made in two pieces, consists of a unit separate from the glass and the caseband, and comprises a ring of transparent material provided on its lower face with horal divisions molded in sunk relief and filled with a clear phosphorescent material in order to contrast with a dark protecting varnish applied on the lower side of said ring, thus constituting an annular dial of the watch (Swiss Patent CH-A-323,976).
In comparison to the two known inventive watchcases considered hereabove, it is not the glass itself in this third known watchcase which comprises an opaque area at its periphery, but a piece which is independent thereof and which is mounted per se on the watchcase. Moreover, the glass can only be made out of a relatively soft material.
In the prior art there are still watchases in which the glass and the caseband, made out of hard materials having almost the same coefficient of thermal expansion, form a single piece when assembling the watch by mounting the movement in the watchcase (French Patent FR-A-2,397,668).
The manufacture of the whole caseband out of a material almost as hard as the sapphire of the glass however constitutes an operation which is as delicate as it is hard and consequently slow and very expensive.
The watchcase according to the invention avoids the drawbacks above-mentioned while substantially broadening the range of appearances which the watchcase can be given. With the exception of the functional organs of the watch (dial, horal divisions, windows, hands, calendar rings) it is, as a matter of fact, the watchcase part usually occupied by independent conventional bezels which essentially determines the aspect of a wrist-watch while being worn. To make a piece of jewelry out of a wrist-watch, as is proper with a high-range watch, it is accordingly on that watchcase part that one has to work, and that, by providing at that place ornamental elements other than a functional dial.
With the inventive watchcase structure the support of those ornamental elements is the fitting fixed to the plate of transparent material of the glass. It means that with a watchcase having a predetermined shape and given sizes for receiving a predetermined watch movement type, the caseband, the bottom and the plate of transparent material of the glass can be manufactured in mass production, however great the number of the different required finishings of the visible watchcase face may be. It is, indeed, the fitting fixed to the plate of transparent material of the glass, which constitutes the visible watchcase face and confers on the watchcase its aspect. Moreover, that fitting is easy to be manufactured because of its simple geometrical shape.
The particular structure of the watchcase according to the present invention has the advantage that the watchcases of a given series all have the same height, whatever fitting is fixed to the plate of transparent material of the glass. With such watchcases, the free space between the dial and the glass always has the same height for the accommodation of the hands. Moreover, the projection formed under the glass periphery by the fitting, like the separate bezel of the conventional watchcases, offers ample space for massive ornamental elements. Preferred embodiments of the present invention relate to structures embodying two equally advantageous modes of fixing the fitting to the glass plate of transparent material. The glues available on the market enable performing durable adherences, which are amply sufficient in this instance. They are, moreover, perfectly transparent and, under certain easily realizable conditions, they quickly dry.
The protecting effect exerted by the glass in the preferred embodiments has already been used abundantly in the field of watchcase manufacturing. In this instance, it permits decorating the visible part of the watchcase by means of ornamental elements even very delicate, without exposing them to alteration, since they lie under the protection of an essentially hard element.
The ornamental elements of the glass may also consist of thin layers formed by vaporization in the vacuum. However, the fitting fixed to the glass plate of transparent material permits to make them massive. They can even constitute the whole glass periphery. With a glass of synthesized corundum, the ornamental elements are preferably made of colored corundum.
The structure ensures a standard fixing mode of the glass to the caseband by particularly simple means.
Due to its periphery perfectly laid on the caseband, the glass has the advantage of being well protected against shocks and the risk of being caught by foreign bodies.